Structure and tree-fall gap dynamics of old-growth Nothofagus forests in Tierra del Fuego,Argentina

Abstract. Tree size and age structure, tree-fall and gap characteristics, and regeneration in gaps were studied in Nothofagus-dominated old-growth forests in Tierra del Fuego, Argentina. Gap-phase regeneration has resulted in all-aged populations for N. pumilio, N. betuloides, and Drimys winteri, and regeneration in gaps appears to be maintaining coexistence between species in mixed stands. N. betuloides fills many gaps via advance regeneration and some individuals persist for > 150 yr in the understory. Multiple periods of release and suppression indicate that N. betuloides may take advantage of several gap events to reach the main canopy. Likewise, Drimys grows well under closed canopy and can rapidly respond to gap formation, sometimes impeding the regeneration of N. betuloides. In contrast, N. pumilio regenerates in gaps mainly from seed or from advance regeneration of small, ephemeral seedlings. Gap turnover times in Fuegian forests were estimated at 300 - 500 yr, although gap formation was highly episodic and possibly associated with regionally extensive windstorms, earthquakes, and stand-level dieback. 92 % of gaps involved multiple tree-falls, and at least 53 % involved secondary expansion. Gap and tree-fall characteristics in Tierra del Fuego were similar to results from northern Patagonia, Chile, and New Zealand; however, we emphasize that regeneration of Nothofagus spp. and Drimys winteri in gaps depends on associated vegetation and varies along both local and regional environmental gradients.     

Magellanic Woodpecker (Campephilus magellanicus) sap feeding and its role in the Tierra del Fuego forest bird assemblage

Several woodpecker species feed on phloem-sap flowing from pecked trees. We report sap consumption by the magellanic woodpecker (Campephilus magellanicus) inhabiting beech (Nothofagus) forests of Tierra del Fuego island (Chile). Magellanic woodpeckers drilled sap wells in N. betuloides trees close to their nests and also when they were moving in family groups. Three other bird species were observed foraging and competing for sap: the austral parakeet (Enicognathus ferrugineus) and two small passerines, the patagonian sierra-finch (Phrygilus patagonicus) and the white-crested elaenia (Elaenia albiceps). The abundance of these three bird species was greater in sites around sap wells than in other forest sites, suggesting that magellanic woodpecker is an important species in maintaining the Nothofagus forest bird assemblage.     

Two new African species of Lejeuneaceae

Abstract

At present, the available information about the liverworts of Sphagnum magellanicum Brid. mires from South America is very limited. The main aim of this paper is to present a comprehensive study of the liverwort flora of this habitat, as well as details on the chorology and ecology of the taxa involved. Four different environmental units were examined, based on the water table level and plant cover, in three representative raised bogs from Tierra del Fuego National Park Ushuaia. Floristic relevs were recorded in 93 square plots 050050m², distributed at random in the environmental units. Twentyfour liverwort species have been identified the majority have a Subantarctic distribution and there were a remarkable number of Magellanean endemics 11 species. Among the rare species, there were two new records for the Argentinian Province of Tierra del Fuego, Cephaloziella byssacea and Chiloscyphus notophyllus. The ecological preferences of the species were analysed based on their frequencies in the four environmental units examined. Only six species demonstrated significant correlation with some of the environmental units. Riccardia pallidevirens, R. georgiensis, R. alcicornis, and Cephaloziella varians, showed a preference for waterlogged and wet habitats, while Calypogeia sphagnicola and Cephalozia chilensis were linked to dense carpets of Sphagnum magellanicum.     

Abundance and distribution of American beaver, Castor canadensis (Kuhl 1820), in Tierra del Fuego and Navarino islands, Chile

Castor canadensis specimens were imported from Canada and released in the wilderness on the Argentinean part of Tierra del Fuego (TDF) in the year 1946. First studies on the development of the beaver population and subsequent environmental changes were conducted four decades later and indicated a strong expansion of these animals, with negative effects on the forest, especially the dominant Nothofagus sp. Between 1999 and 2001, we investigated the density of the beaver population in the Chilean part of TDF and the southern adjacent island Navarino (NAV). Data were mapped into a geographical information system. The mean colony density was 1.03 (range: 0.15–1.91) and 1.1 per km watercourse for 75% of the area of TDF (mainly south and central region) and the total NAV island, respectively. The average number of individuals estimated per colony was five. Based on these findings, the number of beavers in the Chilean part of TDF and on NAV was estimated at 61,300 individuals. The population is increasing and expanding in the Northern region, with a linear rate of 2.6–6.3 km/year.     

Yeasts from Tierra Del Fuego Province (Argentina): Biodiversity,Characterization and Bioprospection of Hydrolytic Enzymes

Abstract

Antarctic and sub-Antarctic regions are – with Polar Regions, mountains and the deep sea – the most extreme environments on Earth because of its low temperatures, dryness, high incidence of solar radiation and low nutrient availability. Nevertheless, microorganisms have successfully colonized these regions. In this study, culturable yeasts from soil samples collected from two different locations, a human-impacted area (Encerrada Bay) and a largely pristine and naturally vegetated area near Lago Escondido city (54°39′0″S, 67°46′48″W) from Tierra del Fuego province, Argentina were identified and characterized at different levels. They were characterized and classified as psychrotolerant and were considered as moderately halotolerant because of their ability to grow in the presence of 1.5?M of NaCl. Yeasts from phylum Ascomycota were affiliated to five genera: Candida, Yarrowia, Debaryomyces, Nadsonia, and Wickerhamiella, whereas from phylum Basidiomycota yeasts were affiliated to six genera: Naganishia, Rhodotorula, Leucosporidum, Tausonia, Cystofilobasidium, and Apiotrichum. Most of the yeasts demonstrated at least one extracellular enzymatic activity (mainly β-glucosidase, esterase, and protease activities). One isolate identified as Tausonia pullulans showed significant activity across the eight enzyme types tested. In light of these findings, Tierra del Fuego province could be considered as a cold environment with a potential source of cold-adapted yeasts producing industrially relevant cold-active enzymes.     

Historical ecology and current abundance of the translocated Chilla or Grey fox Lycalopex griseus on the large Tierra del Fuego Island shared by Argentina and Chile

In 1951, a batch of 24 young animals of both sexes of Chilla or Grey fox Lycalopex griseus from continental Magallanes region, Chile – and perhaps also from adjacent continental Argentina – were released at Onaisin (65 km ESE Porvenir town, 53°18′S) on Tierra del Fuego Island in southernmost South America, to control a European rabbit (Oryctolagus cuniculus) irruption that was considered detrimental to sheep (Ovis aries) ranching. Up to now, no attention has been paid to the temporal course of that introduction. Here we provide a historical account of the presence of foxes on the Tierra del Fuego Archipelago, starting with Charles Darwin account of 1839 until present. We also review the regulatory framework concerning hunting of those foxes and tally their culling for export of pelts. Finally, we provide estimates of the abundance of Chilla foxes on Tierra del Fuego Island for the period 1999–2007 and for 2021, and highlight their current spread. These translocated foxes have become an abundant and functional part of both steppe and forest ecosystems on the Fuegian archipelago, even though they are killed by hunters, without spatial, temporal, or numerical limits. We conclude that interesting scientific opportunities are being missed regarding the population genetics of a species that may have left founding effects and genetic bottlenecks in Tierra del Fuego, and perhaps some peculiar continental markers among the island population. We also raise the question whether this introduced native species may be deemed invasive, calling for research to determine its impact in its new environment.     

Late and postglacial vegetation and fire history in Southern Patagonia and Tierra del Fuego

Two 17,000-yr-old peat bog records from low-elevation sites in Tierra del Fuego (Harberton, 54°54′S) and southern Patagonia (Río Rubens, 52°4′48″S) and one c. 14,000 cal yr BP record from the upper treeline in Tierra del Fuego (Paso Garibaldi, 54°43′S) were analyzed for pollen, charcoal, and plant macrofossils to reconstruct changes in regional and local vegetation, fire frequency, and bog hydrology, respectively. Past environmental changes in both lowland records and in the upper treeline record are interpreted in terms of variations in effective moisture. During the late-glacial period, effective moisture changes at both low and high-elevation sites were interpreted from comparable shifts between mesic herb-rich grasslands and arid Empetrum heath or shrub-grassland with abundant disturbance indicators. The late-glacial effective moisture changes were primarily driven by temperature changes. During the early Holocene, expansion of open Nothofagus woodlands in the lowlands in present-day areas of dense forest was related to a marked precipitation increase. However, precipitation must have remained highly variable with century-long periods of increased summer drought, as evidenced by repeated intervals when bogs dried out and fire frequency was high. Up-slope shifts of the Nothofagus forest — Andean tundra ecotone at 11,000 and 9000 cal yr BP also appear to reflect precipitation increases. Precipitation variability, however, must not have affected the upper treeline environments as no fires were recorded and the present-day Nothofagus forest had become established after 9000 cal yr BP. Upper treeline apparently was below present from 8000 to 7000 and 2500 to c. 400 cal yr BP. During those times low-elevation environments did not register change which suggests that the upper treeline may have been affected by lower temperatures. After c. 5000 cal yr BP fires became rare in the lowlands, suggesting a shift to an equable precipitation regime with only minor intervals of summer drought. No simultaneous change was recorded at the upper treeline. Thus, for the late-glacial and early Holocene the upper and lower treeline environments apparently responded similarly to primarily moisture changes. Only during the mid- and late Holocene environmental changes at high and low elevations differed, suggesting responses to different climate signals, precipitation in the lowlands and temperature at high elevation.     

Growth patterns of <Emphasis Type="Italic">Nothofagus pumilio</Emphasis> trees along altitudinal gradients in Tierra del Fuego,Argentina

The influence of ecological factors resulting from altitude on growth characteristics of Nothofagus pumilio was analyzed. N. pumilio forests grow in the southern Andes from near sea level to 600 m.a.s.l. Eight study sites were selected in the southwestern area of Tierra del Fuego, on north- and south-facing slopes, and distributed along an altitudinal gradient (200–600 m.a.s.l.). Growth cycles throughout time were identified. The correlation between climate and tree growth was determined. Tree diameter and height decreased whereas stand density increased towards tree-line. South-facing slopes showed higher values in common growth variability, probably because of stronger climatic controlling factors. Climate-growth correlation models revealed long-term temperature influences on growth variability, and showed variations among the different plots. Differences were detected in the spectral power component of the chronologies throughout the altitudinal profile. The series had a significant spectral peak at frequencies around 7 years, possibly related to mast seeding cycles. This signal became weaker as the altitude increased probably due to lower seed production. These results suggest a strong altitudinal component in growth variability of N. pumilio in Tierra del Fuego.     

New national and regional bryophyte records, 37

Abstract

We analyzed the form of the UV-absorption spectra and calculated the bulk UV-absorption capacity of the methanolic extracts (BUVACME) in 15 bryophytes (five liverworts and 10 mosses) from unshaded aquatic habitats of Tierra del Fuego (Argentina). BUVACME was obtained as the area under the absorbance curve (AUC) in several ranges of the UV band to allow comparison with the literature data. Both the spectra form and the AUC values depended on the species considered. The spectra showed either no, one or two defined peaks. The peaks were probably due to phenolic derivatives, which could act as both screening compounds and antioxidants. The different AUCs calculated were highly and significantly correlated, and thus it may be unimportant which of these is used. The AUC values of most liverworts were higher than those of most mosses and in particular, the liverworts Noteroclada confluens and Triandrophyllum subtrifidum showed much higher BUVACMEs than those analyzed in any other bryophyte. Thus, the accumulation of UV-absorbing compounds might often increase protection against UV radiation in liverworts, but rarely in mosses. This is in line with the evolutionary differences between these two groups of bryophytes. Except for the two abovementioned liverwort species, BUVACME of aquatic bryophytes from Tierra del Fuego is not particularly different to that found in bryophytes from other zones of the planet.     

The Habitat of Zygodon forsteri (Brid) Mitt. in the New Forest,Hants

Abstract

Seven species are reported here for the first time for South Georgia. Two of these were already known from Tierra del Fuego, Acrolophozia fuegiana Schust. and Marsupella sprucei (Limpr.) H. Bern., but Acrolophozia sulcata Hässel, Marsupella austrogeorgica Hässel, and Marsupella minutula Hässel are described as new. The additional two species which are described, Austrolembidium crassum Hässel and Greeneothallus gemmiparus Hässel, also required the creation of two new genera. The total number of liverwort species now known to be present on South Georgia is sixty-six.     

Mitochondrial DNA variation and population structure of Commerson’s dolphins (<Emphasis Type="Italic">Cephalorhynchus commersonii</Emphasis>) in their southernmost distribution

The Commerson’s dolphin, Cephalorhynchus commersonii, is found in shallow waters of the continental shelf off the eastern coast of South America between 40°S and 56°S. This species is taken incidentally in artisanal gillnet fisheries, especially along the shallow coastline of northern Tierra del Fuego and southern Patagonia. The biological importance of by-catch is likely to be underestimated if the boundaries of subpopulations are not properly defined. Here, we report on the sequence variation of the mitochondrial DNA control region of the Commerson’s dolphin from five areas defined in Tierra del Fuego, Argentina and Chile, to provide a preliminary assessment of population structure where conservation efforts are most needed. A 466 bp fragment of the mitochondrial DNA control region was sequenced from 196 samples of skin, teeth and bone, defining 20 haplotypes from 17 polymorphic sites. Nucleotide (π = 0.40%) and haplotype (h = 0.807) diversity were low compared to some other odontocete populations, but similar to that of other species of this genus. Genetic differentiation evaluated through analyses of molecular variance (AMOVA) showed significant overall differences among areas within Tierra del Fuego (Φ _ST  = 0.059, P < 0.01). An analysis of sex-specific population structure suggested that the dispersal rates of both females and males are low, indicative of females displaying greater site fidelity. The results from mtDNA control region sequences alone revealed significant differentiation among studied areas, which should be considered as independent management units. We recommend that the impact of localized gillnet mortalities should be managed on a local scale in these areas of Tierra del Fuego.     

No need for stepping stones: Direct,joint dispersal of the lichen‐forming fungus Mastodia tessellata (Ascomycota) and its photobiont explains their bipolar distribution

Aim

The hypotheses proposed to explain the high percentage of bipolar lichens in Antarctica have never been explicitly tested. We used the strictly bipolar, coastal lichenized fungus Mastodia tessellata (Verrucariaceae, Ascomycota) and its photobionts (Prasiola, Trebouxiophyceae, Chlorophyta) as model species to discern whether this extraordinary disjunction originated from vicariance or long‐distance dispersal.

Location

Coasts of Antarctica, Tierra del Fuego (Chile), Alaska (USA) and British Columbia (Canada).

Methods

Based on a comprehensive geographical (315 specimens and 16 populations from Antarctica, Tierra del Fuego and North America) and molecular sampling (three and four loci for the fungus and algae respectively), we implemented explicit Bayesian methods to compare alternative hypotheses of speciation and migration, and performed dating analyses for the fungal and algal partner, in order to infer the timing of the colonization events and the direction of gene flow among distant, disjunct areas.

Results

Mastodia tessellata comprises two fungal species which in turn associate with three photobiont lineages along the studied distribution range. Independent estimation of divergence ages for myco‐ and photobionts indicated a middle to latest Miocene species split in the Southern Hemisphere, and a late Miocene to Pleistocene acquisition of the bipolar distribution. Comparison of migration models and genetic diversity patterns suggested an austral origin for the bipolar species.

Main conclusions

The complex evolutionary history of Mastodia tessellata s.l. can be explained by a combination of vicariant and long‐distance dispersal mechanisms. We provide novel evidence of a pre‐Pleistocene long‐term evolution of lichens in Antarctica as well as for bipolar distributions shaped by Southern to Northern Hemisphere migratory routes without the need for stepping stones.     

Two new species of Penicillium from the Tierra del Fuego (Argentina and Chile)

Two new species of Penicillium Link ex Fries are described and illustrated. They were recovered from sandy soils in the Chilean and Argentinian Tierra del Fuego. They clearly differ from all species of the genus described so far and are, therefore, described and proposed as two new taxa: Penicillium turris-painensis sp. nov and Penicillium lapatayae sp. nov.     

Magellanic woodpecker ( Campephilus magellanicus) abundance and foraging in Tierra del Fuego, Chile

The Magellanic woodpecker (Campephilus magellanicus) is a vulnerable and poorly studied bird in the sub-antarctic deciduous and evergreen beech (Nothofagus) forests of South America. On Tierra del Fuego island (Chile), we compared Magellanic woodpecker abundance and its foraging habitat in two forest types: pure N. pumilio and mixed forests composed by N. pumilio and N. betuloides, including managed and non managed stands. At a regional scale, abundance of woodpeckers was greater in landscapes including both forest types than in pure N. pumilio landscapes. When both forest types occurred together, woodpecker abundance did not differ between them. The number of trees with foraging signs was correlated with Magellanic woodpecker abundance and was also associated with N. betuloides and snag densities, but was not affected by forest management. Occurrence of pecking on foraging trees was greater in mixed Nothofagus than pure N. pumilio stands. Woodpeckers foraged disproportionately more on larger diameter and more decayed trees. Moreover, trees used for foraging were positively correlated with canopy cover and snag density and were negatively correlated with distance to nearby peatlands and beaver ponds. Direct observation revealed that the flying distance between trees was negatively correlated with proportion of trees with foraging signs. Woodpeckers chose trees that were visited before, suggesting a pattern of tree recognition within foraging territories.Communicated by F. Bairlein     

A soil nutrient gradient in Magellanic Empetrum heathlands

The relationship of environmental and soil-nutrient variables with the floristic composition of Empetrum rubrum heathlands and related communities from northern Tierra del Fuego were studied by means of ordination techniques. A floristic gradient was found which had its axis of major variation closely related to a gradient in soil trophic status. Increases in the densities of Empetrum and other cushion plants (Bolax gummifera, Azorella lycopodioides, Pernettya pumila) along the floristic gradient were: (a) associated with a lower number of species and total cover, and greater soil erosion; (b) positively correlated with the C/N ratio and aluminium content in the soil; and (c) negatively correlated with pH, calcium content and base saturation.Climate, lithology, habitat exposure, and the history of human activity would be key factors in developing the oligotrophic conditions that favoured the establishment of different Empetrum heathlands.     

The relationship between temporal patterns of wildfires and phytoclimatic regions in Sardinia (Italy)

Abstract

As a precursor to land management and biodiversity conservation, hierarchical landscape classification and mapping has recently received renewed attention. Since climate is the main factor affecting the coarse‐scale spatial distribution of vegetation types, the first step to deal with for developing a hierarchical landscape classification is to categorize the landscape based on the climatic variables that influence the biological systems. Climate also plays an important role in characterizing wildfire regimes. Through its influence on biomass production, climate controls fuel availability. At the same time, climate affects fuel moisture, which is the main determinant for fire ignition and propagation. The influence of climate on coarse‐scale landscape classification and fire regimes invites a comparison of phytoclimatic maps to wildfire data. The main objectives of this paper are: (1) to evaluate the phenological uniqueness of the main phytoclimatic regions of Sardinia (Italy) based on five‐year data (2000–04) of SPOT‐Vegetation NDVI profiles, and (2) to evaluate to what extent the wildfire time series associated to the phytoclimatic regions of Sardinia differ in their temporal properties over the same time span.     

Removal of a non-climatically induced seven-year cycle from Nothofagus pumilio tree-ring width chronologies from Tierra del Fuego,Argentina for their use in climate reconstructions

A pronounced seven-year cycle is one of the most prominent features of many Fuegian and southern Patagonian Nothofagus pumilio tree-ring width chronologies. However, the source of this variability is still unclear. Here we provide multiple lines of evidence that suggest this phenomenon comes from non-climatically induced ecological factors, most probably triggered by insect outbreaks. To test this hypothesis we removed the seven-year cycle, by means of Singular Spectrum Analysis, from a network of 44 tree-ring width chronologies, from the eastern Tierra del Fuego Island in Argentina. The chronologies that were filtered this way showed a stronger climatic response, and were more successfully modeled using the Vaganov-Shashkin-Lite (VS-Lite) process-based forward model of tree growth. We conclude that the removed periodicity does not have a climatic source. Additional evidence from direct observation of affected and non-affected trees during defoliation, due to Ormiscodes sp. outbreak in 2010, is provided. We also tested the hypothesis of probable masting effects on the growth of N. pumilio at a site with a 12-yr record of seed production, but this hypothesis was not confirmed. Taking into account the non-climatic nature of this signal, we explore the utility of corrected chronologies for reconstruction of climatic parameters in Tierra del Fuego, especially for summer temperature and frost day frequency. This study is the first systematic analysis of the pronounced high-frequency cyclicity in N. pumilio tree growth in southernmost South America.     

Conservation value of timber quality versus associated non-timber quality stands for understory diversity in Nothofagus forests

Conservation strategies of forested landscapes must consider biodiversity of the included site types, i.e. timber-quality forests and associated non-timber-quality stands. The objectives were to characterize forest overstory structure in timber-quality versus associated non-timber-quality stands; and to compare their understory communities. Six forest types were sampled in Nothofagus forests of Tierra del Fuego (Argentina): two timber-quality N. pumilio forests, and four associated non-timber-quality stands (edge, N. antarctica, wetlands and streamside forests). Overstory structure and understory vegetation (species richness, frequencies, cover and biomass) were characterized during spring and summer seasons. Analysis of variance and multivariates were carried out. Overstory structure differed across the site types, with higher tree size, canopy closure and tree volume in timber-quality stands. Fifty-one understory plant species were observed, but understory variables varied with site types, especially wetlands (highest native and exotic richness, cover and biomass, and 25% of exclusive species). Site types were grouped in three: N. antarctica stands, streamside stands and the other N. pumilio forests according to multivariate analysis. Forty three percent of plants were distributed in all site types, and all timber-quality forest understory species were present in some associated non-timber-quality stands. Timber-quality N. pumilio forests have a marginal value for understory conservation compared to associated non-timber-quality stands, because these last include all the plants observed in timber-quality forests and also possess many exclusive species. Therefore, protection of associated non-timber-quality stands during forest management planning could increase understory conservation at landscape level, and these could be better reserves of understory diversity than retentions of timber-quality stands.     

Bryophyte Tree of Life: the current state of phylogenetic reconstruction in mosses

Abstract

A Holantarctic species, the inter-subgeneric allopolyploid Sphagnum ×falcatulum s.l. is a cryptic species complex composed of allodiploid and allotriploid cytotypes. The allotriploid plants are double allopolyploids (one of just two reported for bryophytes), with the allodiploid cytotype being one parent. Using a combination of microsatellites, nucleotide sequences, and morphological characters, allotriploid S. ×falcatulum is shown to be the most widespread Sphagnum species in the Holantarctic, with genetically documented populations in South America (Tierra del Fuego), New Zealand (South Island), and Australia (Macquarie Island, Tasmania). It is further concluded that six Sphagnum species described from the Tierra del Fuego Archipelago (TDF) of South America and a seventh described from South Island, New Zealand are synonymous with the allotriploid cytotype of S. ×falcatulum. The synonymized species include five named by Heikki Roivainen in 1937, S. ×ehyalinum, and S. subditivum. Allotriploid S. ×falcatulum is the predominant, perhaps the only, subgenus Cuspidata species present in TDF and immediate vicinity. The combination of low genetic diversity and an apparent absence of sexual reproduction indicate that the TDF population of the dioicous allotriploid S. ×falcatulum was likely founded by one or a limited number of individuals. The same is apparently the case for Macquarie I. and Tasmanian populations of allotriploid S. ×falcatulum. Several lines of evidence, including high genetic diversity, frequent sporophyte production, and the occurrence of the allodiploid parent, suggest that allotriploid S. ×falcatulum likely evolved in New Zealand.     

Gastrointestinal helminths of Commerson's dolphins Cephalorhynchus commersonii from central Patagonia and Tierra del Fuego.

The stomachs and intestines of 9 Commerson's dolphins incidentally caught in trawl nets in central Patagonia and 23 stranded on beaches in Tierra del Fuego were surveyed for helminth parasites. A total of 267 individuals belonging to 4 species of parasites (1 nematode, 3 digeneans) were found in the dolphins from the first area: Anisakis sp. (larvae type 1 = A. simplex), Braunina cordiformis, Hadwenius sp. and Pholeter gastrophilus. In the Tierra del Fuego dolphins, 142 specimens belonging to 3 species (2 nematodes, 1 digenean, 1 cestode) were found: A. simplex, Hadwenius sp. and Strobilocephalus triangularis. Only 2 of the helminth species were shared in the 2 study areas, A. simplex and Hadwenius sp., and both were more common in central Patagonia. Among the species, A. simplex was most prevalent and abundant in both study areas. In Tierra del Fuego, adults of A. simplex appeared in only 1 host. Hadwenius sp., P. gastrophilus and S. triangularis are new host records for Commerson's dolphin. Species diversity and species richness were low in both study areas. Helminth communities were more diverse in central Patagonia (t = 1.97, df = 258, p < 0.05) and species richness was higher in central Patagonia (S = 4). No differences in diversity were observed between females and males of central Patagonia (t = 1.97, df = 139, p < 0.05) and between females of central Patagonia and Tierra del Fuego. The results may suggest some differences in habitat use, diet and sex between Commerson's dolphin populations in the 2 study areas.